The present invention relates to apparatus for severing webs of paper or the like, especially for subdividing adhesive-coated webs of cigarette paper, imitation cork or like strip-shaped wrapping material into discrete uniting bands which can be used for connecting plain cigarettes with filter plugs to make filter cigarettes of unit length of multiple unit length.
Filter cigarettes are produced in so-called filter tipping machines, e.g., in machines of the type known as MAX S and manufactured by the assignee of the present application. Reference may be had to commonly owned U.S. Pat. No. 4,177,670 granted Dec. 11, 1979 to Heitmann et al. which discloses a machine wherein a filter plug of double unit length is placed between two coaxial plain cigarettes of unit length. The filter plug and the adjacent end portions of the plain cigarettes are thereupon draped into an adhesive-coated uniting band which is thereby converted into a tube constituting a means for sealingly connecting the filter plug with both plain cigarettes. The resulting filter cigarette of double unit length is thereupon severed midway across the filter plug and the tube to yield two filter cigarettes of unit length.
A conventional apparatus for subdividing continuous webs of adhesive-coated cigarette paper or like strip-shaped material into discrete uniting bands which are ready to connect filter plugs to plain cigarettes of unit length is disclosed in German Pat. No. 619,292. This patent discloses means for severing the web by resorting to a punching or stamping action. Such apparatus failed to gain widespread acceptance in the tobacco processing industry.
Another conventional apparatus which can be used for the making of adhesive-coating uniting bands is disclosed in British Pat. No. 1,024,090. Apparatus similar to or identical with that which is disclosed in this British patent have found widespread acceptance by the makers of filter cigarettes or analogous articles (the term filter cigarettes is intended to embrace filter tipped cigarillos and cigars). The apparatus of the British patent employs two rotary drums one of which has cutting edges serving to sever an adhesive-coated web at regular intervals so that the latter yields a succession of discrete uniting bands. The other drum is a suction drum which attracts the web and causes the latter to advance toward the severing station. Furthermore, the suction drum serves to transport freshly formed uniting bands away from the severing station as well as to constitute a hard base or anvil for the cutting edges of the one drum. The two drums rotate about parallel axes and the one drum supports a plurality of equidistant knives whose cutting edges strike against the hard peripheral surface of the suction drum in the course of a severing action, i.e., during separation of a uniting band from the leader of the running adhesive-coated web which normally consists of cigarette paper or imitation cork. A drawback of the just described severing apparatus is that the wear upon the peripheral surface of the suction drum as well as on the cutting edges of knives which are mounted on the one drum is very pronounced. This is due to the fact that the cutting edges of the knives strike against the peripheral surface of the suction drum in the course of each severing operation with attendant generation of noise and dulling of the cutting edges of the knives. Moreover, the severing operation is not always satisfactory because it does not involve the making of a cut of the type made by shears but rather a squeezing or pinching action which is performed by the cutting edge of a knife while the latter advances toward the exposed side of the web and penetrates therethrough on its way toward direct contact with the hard peripheral surface of the suction drum.
Another serious drawback of the just described apparatus is that the making of discrete uniting bands is accompanied by the generation of pronounced noise. The knives of the one drum act not unlike hammers by striking against the hard peripheral surface of the suction drum to sever the web transversely of the direction of its forward movement as a result of attraction of the leading edge of the web to the peripheral surface of the suction drum. Since the speed of filter tipping machines is on the increase from year to year to cope with the ever-increasing output of modern cigarette and filter rod making machinery, the noise which is generated by the severing apparatus for adhesive-coated webs is augmented by noise which is generated by other rapidly driven components of one or more machines in a production line so that the noise level is often sufficient to seriously affect the comfort and/or health of the attendants. It has been found that the just described apparatus fails to meet stringent provisions of authorities in many industrialized countries which establish standards for permissible noise levels in manufacturing plants and like establishments.
Attempts to reduce the noise of apparatus which form adhesive-coated uniting bands for use in filter tipping or like machines include resort to conventional severing rather than stamping or pinching techniques, i.e., to have two cooperating cutting edges which move past each other not unlike the blades of shears and to thereby make a cut starting at one marginal portion and progressing toward the other marginal portion of the running web. In other words, instead of relying on one set of knives whose cutting edges strike against a hard countersurface of anvil on penetration through a web of uniting band material, the modified apparatus employ two sets of knives or cutters whose cutting edges slide past one another in the course of a severing operation so that one avoids direct impact of cutting edges against an anvil. Such modified apparatus can furnish a satisfactory severing action at a given temperature of their components. However, due to certain peculiarities of construction and mode of operation of presently used high-speed filter tipping machines (including the aforementioned machines of the type known as MAX S), the temperature of component parts of the severing apparatus is influenced by several variable parameters. Thus, the MAX S machine employs a host of closely adjacent drum-shaped conveyors which transport plain cigarettes, filter plugs and filter cigarettes sideways, i.e., at right angles to the axes of such articles. A heating drum which effects rapid drying of adhesive paste at one side of each uniting band is placed in close proximity to the severing apparatus to ensure that a convoluted uniting band does not open up again, i.e., that it remains in sealing contact with the peripheral surface of the corresponding filter plug and the adjacent end portions of the associated plain cigarettes. Heat which is radiated by the aforementioned heating drum is absorbed in part by the rotary drum or drums of the severing apparatus. In fact, certain filter tipping machines employ severing apparatus with a heated drum in order to activate hotmelt or an analogous heat-activatable adhesive which is applied to one side of the web prior to subdivision into uniting bands. This is often necessary if the station where the freshly formed uniting bands are convoluted around filter plugs and portions of plain cigarettes is closely or immediately adjacent to the severing station. As the drum or drums of the severing apparatus undergo a heating action, their knives expand radially outwardly and are likely to strike against, rather than to bypass, each other. This can result in extensive wear upon and/or in rapid or immediate destruction of the severing apparatus with attendant losses in output.